JP3471406B2 - Method for reducing and recovering valuable metals in slag with improved accuracy of molten steel components - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces and recovers valuable metals in easily reducible oxides suspended in a slag layer covering the surface of molten steel after smelting into molten steel, and obtains appropriate intermediate component accuracy of molten steel. The present invention relates to a method for reducing and recovering valuable metals in slag, which has a high value.

[0002]

2. Description of the Related Art When decarburizing and refining an alloy steel such as stainless steel in a converter, a vacuum degassing device, etc., carbon in molten steel reacts with blowing oxygen to form CO gas and is simultaneously removed from the molten steel. A part of useful components such as Cr, Fe, and Mn is also oxidized according to the following reaction. 4 [Cr] + 3O ₂ → 2 (Cr ₂ O ₃ ) 2 [Fe] + O ₂ → 2 (FeO) 2 [Mn] + O ₂ → 2 (MnO) Metal elements such as Cr, Fe, Mn, etc. Migrates to the slag floating on the surface of the molten steel. The metal element in the slag is reduced from the oxide to a metal state in the final stage of steel making, and is recovered as molten metal in the molten steel. Recovery is Cr, F
Utilizing the fact that metallic elements such as e and Mn are easily reduced to a metallic state by Si, for example, a predetermined amount of Si is added to molten steel in a ladle during vacuum refining. The reduction reaction with Si is as follows. 2 (Cr ₂ O ₃ ) + 3Si → 4 [Cr] +3 (SiO
₂ ) 2 (FeO) + Si → 2 [Fe] + (SiO ₂ ) 2 (MnO) + Si → 2 [Mn] + (SiO ₂ ).

A, which has a greater oxygen affinity than Si
When using l, Ti, etc. as a reducing agent, S in slag
It is also possible to transfer i to metal. Cr, Fe, Mn, etc. in the metallic state are taken into the molten steel, and the composition of the molten steel is adjusted. In order to adjust the composition with high accuracy, it is necessary to quantitatively grasp the metal elements that migrate from the slag to the molten steel at the final stage. Recently, steel grades with extremely strict standards for Si content have begun to be used. In order to cope with such high-accuracy component adjustment and steel grades in which the Si content is strictly controlled, the amount of the easily reducible oxide reduced by Si contained in the slag is accurately grasped. It is necessary. The amount of the easily reducing metal element contained in the slag is calculated from the oxygen concentration and the amount of slag in the metal oxide such as Cr ₂ O ₃ , FeO and MnO. The calculated oxygen amount serves as a reference for determining the amount of Si added as a reducing agent. As a method of quantifying oxygen in a metal oxide, a method of performing fluorescent X-ray analysis on a slag sample is known. In fluorescent X-ray analysis, a converter during refining,
Molten slag collected from a vacuum degasser is used as a sample for analysis by the glass bead method, press molding method, etc.

In the glass bead method, for example, as shown in FIG. 1, the solidified slag is crushed and then weighed, 0.2 g of slag is put in a platinum crucible together with 2.0 g of a flux such as sodium carbonate, and a bead sampler is used. Heat and stir to melt and cool uniformly. According to this method, it takes about 25 minutes to obtain a sample for analysis. In the press molding method, an appropriate amount of the collected slag is filled in an aluminum cap and pressure-molded with a press of 15 to 20 tons to prepare a sample for analysis. The press molding method takes a shorter time to obtain a sample for analysis than the glass bead method, but requires two analyzes on the same sample in order to eliminate measurement errors due to variations in crushed particles. . Therefore, as a result, 2
It takes about 0 minutes. In both the glass bead method and the press molding method, the fluorescent X-ray analysis method requires 20 to 25 minutes from the sample weighing to the calculation of the analysis value. Moreover, assuming that the metal oxide contained in the sample is in a single form, by multiplying the quantitative value of the oxide by the coefficient determined from the stoichiometric relationship between the metal and the oxide, Oxygen analysis value is calculated. However, the samples collected from the slag in the actual operating state often contain Cr, Fe, Mn, etc. in a metallic state and metal oxides having different oxygen values, and this method necessarily causes a measurement error. Occurs.

In order to shorten the analysis time and suppress the analysis error, the inventors of the present invention decided on the steelmaking slag based on the amount of oxygen discharged from the system by the reaction between the sample collected from the steelmaking slag and the carbon source. A method for quantifying easily contained reducible metal oxides such as Cr, Fe and Mn was developed, and Japanese Patent Application No.
Filed as 319364. By this method, 1
Oxygen in the slag can be quantified in a short time within 0 minutes. On the other hand, as a method for measuring slag, tap steel,
It is known to measure the weight of the ladle for each slag and subtract it from the total weight of the ladle including the amount of molten steel and slag.
It is still difficult to measure the amount of slag with high accuracy. The present inventors studied means for detecting the surface position of molten steel on the premise that it is possible to calculate the thickness of the slag layer and thus the slag weight if the surface position of the molten steel under the slag can be detected. As a result, by identifying the frequency of the alternating current supplied to the eddy current sensor, the surface position of molten steel can be accurately detected even through the slag layer in which a large amount of conductive metal droplets are suspended. And found a method of using an eddy current sensor to which an alternating current having a frequency of 0.5 to 500 KHz is supplied.
Proposed in No. 59. An eddy current is generated on the molten metal surface by the alternating current supplied to the eddy current sensor, and the surface position of the molten steel is calculated based on the induced magnetic field generated by the eddy current.

[0006]

The weight W _{M of} the molten steel is calculated from the calculated surface position of the molten steel. On the other hand, since the weight W _{V of} the vacuum degassing vessel, the ladle, etc. and the total weight W _T including the molten steel and the slag are easy to measure, the slag weight W _S
Is calculated by W _S = W _T − (W _M + W _V ). But,
In this method, slag weight W of the molten steel weight W _M as an intermediary
_{Since S} is calculated indirectly, error factors are likely to be incorporated. For example, in a container such as a vacuum degassing container or ladle that contains molten steel, the inner wall surface becomes complicatedly uneven due to corrosion by molten steel or slag as the number of times of use increases. Therefore, when the molten steel weight W _M is simply calculated from the surface position of the molten steel, the influence due to the unevenness of the inner wall surface may not be incorporated in the calculation factor and may cause an error. Such an error factor can be removed by measuring the shape of the refractory material in the container just before scouring. However, measurement is not an optimal method because it requires a long time and increases the work load. The present invention has been devised to solve such a problem, by eliminating the error factors associated with the measurement of the molten steel weight as much as possible, by measuring the thickness of the slag layer itself, By accurately calculating the weight and adding the reducing agent in an amount determined based on the calculated weight and the slag composition, the reducing agents such as Si and Al are not brought into the molten steel more than the specified components, and The purpose of the present invention is to obtain molten steel in which the content of alloying components such as Mn and Cr is improved and the precision is improved.

[0007]

In order to achieve the object, the method for reducing and recovering valuable metals in slag of the present invention reduces the valuable metals in easily reducible oxides to the molten steel from the slag floating on the surface of the molten steel. When collecting, the sample taken from the slag is carbon-reduced and the content of the easily reducible oxide is measured, and the surface positions of the slag and the molten steel are detected, and the difference between the detected surface positions is determined. Calculate the thickness of the slag, determine the weight of the slag based on the thickness of the slag, calculate the required addition amount of the reducing agent from the content of the easily reducing oxide and the weight of the slag, the addition of the calculation result The reducing agent is added to the slag in an amount.
The surface position of the slag is detected by a range finder using eddy current, laser, microwave, radiation, etc., a touch type sensor that directly contacts the slag surface, a method of measuring the brightness of the slag, and the like. For an eddy current sensor, the frequency is 5
It is preferable to use an eddy current sensor that is supplied with a high-frequency alternating current of 00 kHz or more and 1 MHz or less. A high-frequency alternating current with a frequency of 500 kHz or more and 1 MHz or less generates an eddy current only on the surface of the slag, so that the surface position of the slag can be detected.

The surface position of the molten steel has a frequency of 0.5 to 500.
A high frequency alternating current of kHz is supplied and detected by an eddy current sensor. By supplying a high-frequency alternating current with a frequency of 0.5 to 500 kHz, the error factor due to the eddy current caused by the metal droplets suspended in the slag layer is not captured by the receiving coil of the eddy current sensor, The surface position of a certain molten steel is detected with high accuracy. Alternatively, instead of an eddy current sensor, a method of immersing a pair of electrodes from the slag to the metal and electrically detecting the difference in conductivity between the slag and the metal, a gas probe in which a constant amount of gas is constantly flowing from the slug The surface position of the molten steel can also be detected by a method of immersing the metal over the metal and detecting a back pressure change in the gas probe due to a difference in specific gravity between the slag and the metal. The valuable metal reduced and recovered by the molten steel can be selected according to the reducing ability of the reducing agent used. For example, when Si or ferrosilicon is used as a reducing agent, Fe, Mn and Cr are reduced and recovered in molten steel. When Al, Ti, Ca, Mg or an alloy thereof is used as a reducing agent, Fe, Mn, Cr and Si are reduced and recovered. When Al, Ca, Mg or an alloy thereof is added as a reducing agent, Fe, Mn, Cr, Si and Ti are reduced and recovered in molten steel. In each case, the required addition amount of the reducing agent is determined from the oxygen amount of the easily reducing oxide in the slag and the weight of the slag. Molten steel can be obtained with high precision.

[0009]

In the present invention, the surface positions of the slag and the molten steel are detected as the distances X ₁ and X ₂ from the reference point. Since the surface position of the molten steel at the interface between the slag layer, the thickness of the slag layer is calculated as (X ₁ -X _2). On the other hand, since the inner radius R of a vacuum degassing container, a ladle, or the like is known in advance, the slag volume V _S is V _S = πR ² × (X ₁ −X ₂ ).
Becomes The weight W _S of the slag is obtained by multiplying the volume V _S by the specific gravity ρ of the slag, and thus W _S = ρ × V _S = ρ × πR ² ×
It is calculated as (X ₁ −X ₂ ). The obtained slag weight W _S is a value directly calculated from the thickness of the slag layer without interposing the molten steel weight W _M. Therefore, an error factor is rarely taken in, and the slag weight W _S with high accuracy is obtained. On the other hand, the content of the easily reducing oxide contained in the slag can be quickly obtained by the carbon reduction method previously proposed by the present inventors. The required addition amount of the reducing agent is calculated from the slag weight W _S and the content of the easily reducible oxide thus obtained. When the reducing agent is added in this addition amount, the easily reducible oxide in the slag is reduced and is recovered in the molten steel in the metallic state. Further, since an excessive reducing agent is not added, it is possible to reduce the excessive reducing agent brought into the molten steel. That is, Si, A more than the standard component
It is possible to obtain the molten steel in which the reducing agent such as 1 is not brought into the molten steel excessively and the accuracy of the content of the alloy components such as Mn and Cr is improved.

-Oxygen determination of easily reducible oxide contained in slag-The oxygen content of easily reducible oxide contained in slag is determined by continuously measuring a sample collected from slag in an inert atmosphere. It can be quantified by reacting with a carbon source while heating and measuring the amount of oxygen bound to carbon and discharged to the outside of the system in a time series. For example, when a slag sample is placed in a graphite crucible together with a carbon source such as activated carbon or carbide and the temperature is continuously raised in an inert atmosphere, CO gas is generated by the reaction between the easily reducible oxide and carbon. At this time, oxides such as Cr, Fe, and Mn contained in the slag sample (herein, these oxides are referred to as easily reducing oxides) start a reduction reaction at a relatively low temperature and are separated from the metal elements. The oxygen is extracted. On the other hand, oxides of Ca, Mg, Si, etc. (here,
These oxides are referred to as non-reducible oxides) are Cr ₂ O
_{Since the} oxygen affinity is higher than that of oxides such as ₃ , FeO and MnO, the starting temperature of the reduction reaction becomes high. That is,
After the oxygen extraction from the easily reducing oxide is completed, the oxygen extraction from the hardly reducing oxide is started. Therefore, when the CO gas generated by the carbon reduction of the sample slag is continuously quantified by the infrared absorption method, an oxygen extraction curve as shown in FIG. 2 is obtained. The oxygen extraction curve rises with the analysis time and the heating temperature, but once falls at the temperature T ₁ near 1800 ° C. reaching the time point t ₁ and then rises again at the time point t 1.
_{At 0} , the oxygen intensity is 0. Minimum value I ₁ of the analytical oxygen intensity at time t ₁ is clearly detected, it can be clearly distinguished and a reducing reaction of the easily reducible oxide and irreducible oxide.

The value obtained by integrating the oxygen intensity from the start of analysis to time t ₁ , that is, the area of the shaded region in FIG. 2, corresponds to the amount of oxygen extracted from the easily reducible oxide. The oxygen amount of the easily reducible oxide contained in the slag is calculated from the oxygen value thus obtained, and the necessary addition amount of the reducing agent is calculated accordingly. Since the reducing agent is added in an appropriate amount to the slag whose composition is known,
Valuable metal recovered from the slag into molten steel is also quantitatively controlled, and unreacted reducing agent introduced into molten steel in excess of the standard component is suppressed. The carbon reduction method is used when quantifying easily reducible oxides such as Fe, Mn, and Cr that are reduced by Si. When this carbon reduction method is combined with the fluorescent X-ray analysis method, Al, Ti, Ca, M having a greater oxygen affinity is obtained.
Non-reducible oxides that are reduced with g, etc., ie, Cr, F
Oxides of metals having an oxygen affinity between e, Mn and the like and Al, Ti, Ca, Mg and the like are also quantified. For example, Al
When is used as a reducing agent, oxygen content of SiO ₂ , TiO _2, etc. is determined.

-Measurement of slag weight-The surface position T _{1 of the} slag is an eddy current sensor to which a high frequency alternating current of 500 kHz to ₁ MHz is supplied, a laser,
It is measured using a range finder using microwaves, radiation, etc., a touch sensor that directly contacts the detection terminal to the surface of the slag, and a sensor that detects the brightness of the slag. When detecting the surface position T _{1 of the} slag with an eddy current sensor, 5
It is necessary to use an eddy current sensor supplied with a high frequency alternating current of 00 kHz to 1 MHz. 500kH
The high frequency alternating current of z to 1 MHz generates an induction magnetic field only on the surface of the slag and detects the surface position T _{1 of the} slag. With a high frequency alternating current whose frequency is less than 500 kHz, the surface position T _{2 of the} molten steel under the slag is detected.
On the other hand, with a high frequency alternating current exceeding 1 MHz, the surface position T ₁ of the slag can be measured theoretically, but it is not practical. Specifically, it is difficult to provide a technique for supplying a high-frequency alternating current to an eddy current sensor, for example, a measure for preventing external noise on a cable for connecting a high-frequency alternating-current supply side equipment and the sensor body. The surface position T _{2 of the} molten steel at the interface with the slag is the eddy current sensor to which a high-frequency alternating current of 0.5 to 500 kHz is supplied, and a pair of electrodes is dipped from the slag over the metal to obtain a difference in conductivity between the slag and the metal. Is detected by a method such as electrically detecting the back pressure in the gas probe caused by the difference in specific gravity between the slag and the metal by immersing the gas probe in which a constant amount of gas is flowing from the slag to the metal. It The thickness of the slag layer is obtained from the difference (T ₁ -T ₂ ) between the surface positions detected by the respective sensors. At this time, the measurement accuracy is improved by taking a large number of measurement points in the plane of the slag and the molten steel. Thickness of this slag layer (T
₁₋ T ₂ ) and the inner radius R of the vacuum degassing container, the ladle, or the like measured in advance, the slag volume V _S can be calculated as πR ² × (T ₁
-T ₂ ). The weight W _S of the slag is the volume V _S
Is multiplied by the specific gravity ρ to obtain ρ × πR ² × (T ₁ −
It is calculated as T ₂ ).

-Calculation of Required Addition Amount of Reducing Agent-The required addition amount of a reducing agent is calculated according to the flow shown in FIG. That is, when the slag weight W _S obtained from the surface position T _{1 of the} slag and the surface position T _{2 of the} molten steel is multiplied by the oxygen content (O) of the easily reducing oxide contained in the slag, the easily reducing property is obtained. The oxygen content of the oxide is determined as W _O = W _S × (O). Therefore, the necessary addition amount W _R of the reducing agent corresponding to W _O = W _S × (O) is obtained. By adding the amount W _R of the reducing agent thus adjusted,
Fe, Mn, Cr, etc. in the easily reducible oxides are reduced and recovered from the slag into the molten steel in a predetermined amount without causing excessive addition. As a result, the reducing agent can be efficiently consumed, and since an excessive amount of the reducing agent is not brought into the molten steel, the content of molten steel after melting is improved. for that reason,
In particular, it is possible to accurately manufacture even steel types that require strict control over the content of Si, Al, etc. derived from the reducing agent.

[0014]

【Example】

(Effect of frequency of eddy current sensor for slag surface measurement)
On a SUS304 stainless steel plate, which is a non-magnetic material, 10 kg of slag molded to a thickness of 50 mm was placed. As the slag, SiO ₂ 25% by weight, Al ₂ O ₃
The basic composition was 10% by weight and 45% by weight of CaO. An eddy current sensor is arranged at a height of a measured distance D measured in advance from the slag surface, and the frequency of the high-frequency alternating current supplied to the eddy current sensor is changed from 100 kHz to 1 MHz, and the slug measured by the eddy current sensor. The influence of frequency on the distance d to was investigated. As is clear from Table 1 showing the investigation results, it was found that the measured distance d is highly accurately matched to the measured distance D in the range of the frequency of the high frequency alternating current supplied to the eddy current sensor from 550 kHz to 1 MHz. It was From this, it was confirmed that the high frequency alternating current supplied to the eddy current sensor has a predetermined frequency range in order to measure the surface position of the slag with high accuracy without a measurement error.

[0015]

[Table 1]

(Measurement of distance applied to actual slag) Molten steel 77-81 tons of austenitic stainless steel and ferritic stainless steel for which converter smelting has been completed (total 50)
(Charge) was poured into a vacuum degasser, and after 1 minute, a sample slag was sampled from the slag floating on the surface of the molten steel, and the surface positions of the slag and the molten steel were detected. Here, the surface position of the slag was detected by an eddy current sensor to which an alternating current having a frequency of 550 kHz to 1 MHz is supplied and a touch sensor that directly contacts the surface of the slug with a detection terminal. In addition, an eddy current sensor to which an alternating current with a frequency of 0.5 to 500 kHz is supplied and an electrode type sensor that detects the conductivity of each of the slag and the metal by immersing a pair of electrodes over the slag and the metal are used. Was detected. Table 2 shows the results of calculating the thickness of the slag layer from the surface positions of the slag and the molten steel detected by each method. As shown in Table 2, the difference in slag thickness was about 5 mm at the maximum.

[0017]

[Table 2]

(Calculation of Necessary Addition Amount of Reducing Agent) Charge N
Regarding o.1, the oxygen content of the sample slag was determined by the carbon reduction method, and the oxygen content of the easily reducible oxide was 11.3%. The apparent specific gravity of the slag was 4.0 as measured by the JIS method. Therefore, the weight of the slag is π × 16900 cm × 25.1 cm × 4.0 g / c from the thickness of the slag measured by the eddy current sensor of 25.1 cm, the apparent specific gravity of 4.0 and the inner radius of the vacuum degassing container of 130 cm.
It was calculated that m ³ = 5.3 tons. From this calculated value and the amount of oxygen by the carbon reduction method of 11.3%, Cr ₂ O ₃ , FeO,
The addition amount of the reducing agent necessary for reducing and recovering the easily reducing oxide such as MnO is 5.3 tons × 11.3% × (28
/32)=527.1 kg was calculated. Si content 6
Since 0% ferrosilicon is used as the reducing agent, the required addition amount of the reducing agent is 527.1 kg ÷ 60% = 8.
It was calculated to be 78 kg.

(Molten steel composition before and after adding reducing agent) Calculated amount 87
After 8 kg of ferrosilicon was charged into the molten steel, vacuum degassing and deoxidation were continued for 20 minutes. The slag was sampled again and the easily reducible oxide was quantified with oxygen. As a result, the oxygen content of the easily reducing oxide contained in the slag was 0.04%.
It had fallen to. With respect to Charge No. 1, the composition of the easily reducing oxide contained in the slag collected before and after Si deoxidation was separately analyzed by the wet analysis method. As is clear from Table 3 showing the analysis results, it was confirmed that the easily reducing oxide was sufficiently reduced and recovered.

[0020]

[Table 3]

The recovery rates of Mn and Cr for 50 charges obtained by the same method using an eddy current sensor were 98.1% and 96.2%, respectively. Same 5
The Si content in the molten steel after deoxidation was measured for 0 charge. As a result, the standard deviation (σ) of the difference between the analysis values and the target value of Si content was 1σ = 0.031% by weight, which was an extremely low value. As a result, Cr and Mn, which are valuable metals, are efficiently recovered in the molten steel, and the molten steel is deoxidized with a high degree of moderate component accuracy without increasing the Si content due to excessive carry-in of the deoxidizing agent. It was confirmed.

(Example of measurement of slag thickness using touch type sensor and electrode type sensor) For molten steel 78-80 tons (total 7 charges) of austenitic stainless steel and ferritic stainless steel after converter smelting is completed,
The surface position of the slag was measured by a touch sensor, and the surface position of the molten steel was measured by an electrode sensor. The difference between the two surface positions was used as the thickness of the slag layer, and the weight of the slag was calculated in the same manner. Ferrosilicon was added as a reducing agent in an amount calculated from the calculated slag weight and the oxygen amount of the easily reducing oxide contained in the slag, and the molten steel was deoxidized. As a result, 7
The recovery rates of Mn and Cr for the charge were 97.8% and 97.0%, respectively, on average. Further, when the Si content in the molten steel after the deoxidation of 7 charges was analyzed, the standard deviation (σ) of the difference between the analysis value and the target value was 1
σ = 0.003% by weight, which is an extremely low value. That is, the recovery rates of Mn and Cr and the hit rate of the Si content in the molten steel were industrially sufficiently satisfactory values. In the above examples, Fe, Mn, Cr are used by using the Si reducing agent.
The case of reducing and recovering the above has been described. However, the present invention is not limited to this, and it is possible to use other reducing agents such as Al and Ti. For example, when using an Al-based reducing agent having a greater oxygen affinity than Si, Si contained in the slag is also reduced and recovered by the molten steel. In this case, oxygen is quantified in the slag in a form containing oxides of Si and Ti.

[0023]

As described above, in the present invention, by adding the reducing agent in the optimum amount, the easily reducing oxides such as Fe, Mn, and Cr contained in the slag are brought into the metallic state. And recovered into molten steel, and due to the excessive addition of the reducing agent, the Si content in the treated molten steel, A
It suppresses an increase in l content and the like. as a result,
Molten steel with a high hit rate against the target composition is smelted. Further, since the consumption amount of the reducing agent can be minimized, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 Flow for determining oxygen in metal oxides contained in slag

FIG. 2 is a graph of oxygen determination by a carbon reduction method developed by the present inventors.

FIG. 3 is a flow chart for determining a necessary addition amount of a reducing agent according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomiya Fukuda 11-11 Showa-cho, Kure-shi, Hiroshima Nisshin Steel Co., Ltd. Steel Research Laboratory (56) Reference JP-A-6-279828 (JP, A) JP-A-6-148167 (JP, A) JP-A-5-51625 (JP, A) JP-A-6-122917 (JP, A) JP-A-61-272604 (JP, A) JP-A-60-183503 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21C 7/00

Claims (5)

(57) [Claims] 1. When a valuable metal in an easily reducible oxide is reduced and recovered from the slag floating on the surface of molten steel to the molten steel, a sample collected from the slag is carbon-reduced to remove the easily reducible oxide. Along with measuring the content, the surface position of the slag and the molten steel is detected, the thickness of the slag is calculated from the difference between the detected surface positions, and the weight of the slag is calculated based on the thickness of the slag. Calculate the required addition amount of the reducing agent from the content of the reducing oxide and the weight of the slag,
A method for reducing and recovering valuable metal in slag with improved accuracy of appropriateness of molten steel composition, characterized in that the reducing agent is added to the slag in an addition amount of a calculation result. 2. The reduction and recovery method according to claim 1, wherein an eddy current sensor for supplying a high frequency alternating current having a frequency of 500 kHz or more and 1 MHz or less is used as a device for detecting the surface position of the slag. 3. The reduction and recovery method according to claim 1, wherein the easily reducing oxide is an oxide of Fe, Mn and Cr, and the reducing agent is Si or ferrosilicon. 4. The easily reducing oxide is an oxide of Fe, Mn, Cr and Si, and the reducing agent is Al, Ti, Ca, Mg.
Alternatively, the reduction recovery method according to claim 1, which is an alloy thereof. 5. The easily reducing oxide is Fe, Mn, Cr, S.
It is an oxide of i and Ti, and the reducing agent is Al, Ca, Mg
Alternatively, the reduction recovery method according to claim 1, which is an alloy thereof.